Use the massive store for initial creation of concept schemes

when the instance's backend is postgres.

dataimport.py

@@ -23,7 +23,6 @@ from os.path import join, dirname
 
 from six import text_type
 
-from cubicweb.dataimport.stores import NoHookRQLObjectStore
 from cubicweb.dataimport.importer import SimpleImportLog
 
 from cubes.skos import lcsv, sobjects as skos
@@ -108,7 +107,12 @@ def lcsv_check(cnx, store, fname, scheme_uri):
 
 def import_seda_schemes(cnx, lcsv_import=lcsv_import):
     """Import all LCSV data files defined in LCSV_FILES"""
-    store = NoHookRQLObjectStore(cnx)
+    if cnx.repo.system_source.dbdriver == 'postgres':
+        from cubicweb.dataimport.massive_store import MassiveObjectStore
+        store = MassiveObjectStore(cnx, eids_seq_range=1000)
+    else:
+        from cubicweb.dataimport.stores import NoHookRQLObjectStore
+        store = NoHookRQLObjectStore(cnx)
     for title, rtypes, etypes, fname in LCSV_FILES:
         if not cnx.find('ConceptScheme', title=title):
             print('importing', title.encode('utf-8'))